Abstract
Extrudate swell from segmented arc type spinneret was investigated by studying the roundness as well as hollowness of polypropylene hollow fibers from different molecular weight polypropylene chips. Extrudate swell increases as the spinning temperature decreases and average molecular weight increases. Also, extrudata swell of polypropylene with higher first normal stress difference is larger. Hollowness of fibers is influenced by the extrudate swell and the fiber formation process along the spinline. Hollowness decreases as the spinning temperature increases and the rate of decrease in hollowness is greater for polypropylene with smaller activation energy. In the case of polypropylenes with similar first normal stress difference, hollowness of fibers increases as the weight average molecular weight increases. Roundness of the inner circle is more sensitive to spinning temperature and molecular weight than that of the outer circle.